There are only a few PDAs that can open PDF documents and provide decent image quality and remain under a $300 mark. (Considered the average for a mid-ranged unit.)
* The Palm Zire 72 features a standard-quality color screen, built-in digital camera with voice recorder, a 312MHz processor, and has the ability to read PDF documents, as well as MS Word, Excel, and Powerpoint files. It is priced at $249.
* The Palm Tungsten E2, also priced at $249, has similar capabilities. While it has a slower 200MHz processor and lacks a digital camera, it has the same color screen, a new version of the Palm OS, and has a connector for keyboards and other peripherals.
* Finally, the Dell Axim X30 High features a 624MHz processor (fastest currently available), 3.5'' QVGA screen (very good), and has built-in WiFi and Bluetooth. Because it is considered old (though still one of the best in the game), it is on sale for $297.
Unfortunately, the Palm Zire 31 (priced at just $129) has a decent color screen and the ability to sync with MS Outlook (like the others can), but doesn't support PDF documents natively. However, Adobe offers a free version of Acrobat reader for the Palm...juct click here. Considering this, the Zire 31 is probably the best option for you. However, if you are willing to spend a little more, the Axim X30 is by far the best deal, and includes WiFi.
Hope this helps,
John